This invention relates to apparatus for use in welding together two annular members such as large diameter pipe sections used in the manufacture of fluid vessels, railroad tank cars, and the like, and more particularly to apparatus for use in fitting, prior to welding, two such pipe sections in end-to-end or telescoping relation. The apparatus disclosed herein is similar in many respects to that disclosed in co-pending application Ser. No. 141,051, filed Apr. 17, 1980 now U.S. Pat. No. 4,356,615.
Fluid vessels, tank cars, and the like conventionally are formed by welding together pipe sections having diameters of as much as thirteen feet. When such large diameter pipe sections are to be welded to one another it is extremely difficult to position and maintain them in proper positions end-to-end so that they properly may be welded to one another. The difficulty is enhanced in most instances because rarely, if ever, do the adjacent ends of the two sections conform exactly, either as to configuration or wall thickness. It is necessary, therefore, to reform the confronting ends of the pipe sections so that their configurations match each other as closely as possible and so that any mis-match between the wall thicknesses is compensated for as much as possible. These operations require not only physical reshaping of one or both of the pipe sections, but relative movement of their confronting ends while maintaining clamping forces on the pipe sections.
Apparatus constructed and operated in accordance with the invention minimizes greatly the difficulties heretofore encountered in fitting together and welding members of the kind referred to, greatly accelerates pre-welding fit-up operations, minimizes the time to effect a weld, and minimizes the possibility of inferior welds being obtained.
Preparatory to welding together two pipes according to the invention one pipe is secured in fixed position on a support and encircled by a clamp adjacent that end which is to be welded. The clamp is provided with pressure exerting members which apply compressive forces on the pipe so as to reform and reshape its end to a cylindrical or substantially cylindrical configuration. The second pipe is brought to a position adjacent the end of the first pipe with the adjacent ends of the two pipes confronting one another. A second clamp encircles the second pipe adjacent that end of the latter which is to be welded and exerts a radial force on the second pipe to reform its end to a configuration compatible with the end of the first pipe. The second clamp is carried by the first clamp and is movable relatively to the latter while maintaining the clamping force on its pipe. Adjustment of the second clamp relative to the first clamp thus enables corresponding relative adjustment of the two pipes so as to locate their confronting ends in the most favorable positions for welding.
If the two pipes are to be welded end-to-end, the confronting ends of the pipes are reformed so as to correspond closely to one another. If the second pipe is to be telescoped within the first pipe, the second pipe initially must have a nominal outside diameter corresponding substantially to the inside diameter of the first pipe. In this instance, the clamps encircling the pipes apply radially compressive forces to the respective pipes to conform their shapes and enable the second pipe to telescope into the first pipe.
Reformation of the ends of adjacent pipes usually requires that the pipes be shifted transversely, or rocked, or both, to arrange the confronting ends properly for welding. Further, following proper arrangement of the confronting ends, the pipes frequently require movement toward one another, especially when one pipe is to be telescoped into the other. Apparatus constructed in accordance with the invention enables all of these requirements to be met.
Reformation of the confronting ends of the two pipes is accomplished by the application of radially compressive force on such pipes. Such force preferably is substantially uniform about the periphery of the pipes and is applied by radially extending, adjustable force applying members. Preferably, the radial adjustment is effected by power means, and to facilitate assembly and initial adjustment of such force applying means the clamps on which such force applying members are mounted are supported for swinging movements between raised and lowered positions.